Background: Hepatitis C virus (HCV) viremia is thought to have broad, systemic effects on the cellular immune system that go beyond its impact on just those T-cells that are HCV-specific. However, prior studies of chronic HCV and circulating T-cell subsets (activation and differentiation phenotypes) in HIV-negatives used general population controls, rather than a risk-appropriate comparison group. Studies in HIV-positives did not address overall immune status (total CD4+ count).
Methods: We used fresh blood from HIV-positive and at-risk HIV-negative women, with and without chronic HCV, to measure percentages of activated CD4+ and CD8+ T-cells, Tregs, and T-cell differentiation phenotypes (naive, central memory (CM), effector memory (EM), and terminally differentiated effector). This included 158 HIV-negatives and 464 HIV-positives, of whom 18 and 63, respectively, were HCV viremic.
Results: In multivariate models of HIV-negatives, HCV viremia was associated with 25% fewer naive CD4+ (P=0.03), 33% more EM CD4+ (P=0.0002) and 37% fewer CM CD8+ (P=0.02) T-cells. Among HIV-positives we observed only one of these three relationships: higher percentage of EM CD4+ among HCV viremic women. Further, the association with EM CD4+ among HIV-positives was limited to individuals with diminished immune status (total CD4+ count <=500 cells/[micro]L), as were associations of HCV viremia with higher percentages of activated CD4+ and Tregs. Among HIV-positives with high CD4+ count, no significant associations were observed.
Conclusions: These data suggest that HCV viremia in HIV-negatives is associated with accelerated T-cell differentiation, but among HIV-positives the impact of HCV viremia is less straightforward and varies by total CD4+ count.
(C) 2014 by Lippincott Williams & Wilkins